Level III Ecoregions of EPA Region 1

Ecoregions by EPA region were extracted from the seamless national shapefile. Ecoregions denote areas of general similarity in ecosystems and in the type, quality,...按美国环境保护署（Environmental Protection Agency, EPA）生态区域划分的生态区（Ecoregions）从无缝全国shapefile中提取得到。生态区指在生态系统以及生态类型、质量等方面具有总体相似性的区域。